Shots - Health Blog

1:51 pm

Wed December 7, 2011

Why Observing Prostate Cancers Is Gaining Ground On Surgery

A federally convened panel of experts says most men with newly diagnosed prostate cancer should be offered the chance to put off treatment in favor of medical monitoring of their condition.

In fact, the panel went so far as to say doctors should stop calling most of these low-risk tumors cancer at all.

"Strong consideration should be given to removing the anxiety-provoking term 'cancer' for this condition," the 13-member panel says in its draft recommendations, which were produced after two days of presentation and debate.

Some think these tumors should be rebranded as something else, such as idle tumors, to reflect the fact that they're not all that threatening and don't necessarily need to be treated. The analogy, though imperfect, is that some early skin cancers are called "actinic keratoses" and early cervical cancers are termed "dysplasias."

This week's sessions made clear there isn't much evidence to show whether deferring surgery and radiation for low-risk prostate cancer gives a man as good a shot at surviving the disease as immediate treatment.

But surprisingly, the panel says there's no need to do a big study that randomly assigns men with newly diagnosed low-risk tumors to observation or treatment, if their life expectancy is less than 20 years. Such a study would have to be very big and very long to pick up a mortality difference.

For men expected to live longer than two decades, the panel does call for a randomized study. It will be interesting to see whether more men volunteer for such a study than were willing back in 1994, when the only such US study on this issue had a lot of trouble persuading men to be randomized.

That study, called PIVOT, figured heavily in the panel's deliberations. The results were presented at an American Urological Association meeting in May. The results haven't been published in a peer-reviewed journal yet.

More about PIVOT in a sec, but first some perspective.

The great majority of the 240,000 US men diagnosed with prostate cancer each year have low-risk disease, as defined by a Gleason score of 6 or less. (Gleason scores combine how many cancerous cells are seen in a needle-biopsy tissue sample, and how aggressive the cells appear to be.)

More than half of all prostate cancers get a Gleason score of 6, the lowest score usually given. In fact, the panel notes that as many as 70 percent of prostate cancers these days are Gleason 6s, and thus low-grade. Why is that? Widespread PSA testing is catching very early cancers.

Think about that for a minute: The great majority of prostate cancers are low-risk. These cancers aren't likely to kill them. And yet only 1 in 10 men diagnosed with prostate cancer defers immediate treatment that aims to cure the condition in favor of observation.

Observation takes two different forms. There's "active surveillance," which aims to pick up signs that a low-risk tumor is becoming more aggressive. That means regular PSA tests, digital rectal exams and periodic needle biopsies. The hope is that a progressing cancer can be identified in time to cure it. The other approach is "watchful waiting." Doctors wait for symptoms to appear, which indicates the cancer has advanced.

The panel says these observational strategies are "under-utilized...for reasons that are not fully understood." It strongly implies that many doctors, and especially urologic surgeons, present observational approaches "in a negative way...as 'doing nothing.' "

But by choosing immediate treatment, men with low-risk prostate tumors are subjecting themselves — perhaps unnecessarily — to high rates of urinary and bowel incontinence and impotence, and many of these side effects don't go away.

Of patients who do choose to defer treatment, a quarter will change their minds within two to three years, and perhaps a half by five years. "The reasons for leaving active surveillance are often unclear," the panel says.

The best evidence for considering active surveillance or watchful waiting is that the PIVOT trial, which compared 731 men with prostate cancer randomly assigned to surgical removal of their prostate or observation.

After an average of 10 years of followup, about half the patients had died. But only 7 percent died of prostate cancer (as far as the researchers could determine), and the risk of dying (from prostate cancer or any cause) was not significantly different between the "treatment" and "observation" groups – if the tumor was initially deemed low-risk.

An earlier Scandinavian study did find that men who underwent immediate treatment had lower risk of dying than those who underwent watchful waiting. But that was back in the days when prostate cancer was typically more advanced at the time of diagnosis, and observation of untreated patients may have been less likely to pick up progressing cancers.

It remains to be seen, of course, how much influence the NIH panel's statement will have on the real-world practice of prostate cancer treatment, and the choices of patients.

The panel heard from one man, Catholic University law professor David Lipton, who said he deliberately rejected active surveillance three years ago, even though he had a low-risk tumor. And he'd do it again.

"Ultimately...the decision was very visceral and personal," Lipton says. "I did not want to wake up each morning wondering if the previous night was the night that a cancer cell 'flew' from my prostate and invaded other reaches of my body."

The fact that he no longer has a prostate that might seed a fatal metastasis "gives me some comfort, even though a number of studies suggest it should not," Lipton says.

His decision might be different, Lipton says, if scientists develop reliable tests that predict if a prostate tumor really is indolent or aggressive, and if future data indicates that men who get treated after a period of observation do as well as those who get treated up-front.

As with any expert panel, this one did recommend, urgently, a number of studies, in addition to the big trial comparing treatment and observation among younger men with low-risk tumors. Much remains to be done, it said, to define just what observation means, to make sure men labeled low-risk really are, to come up with better ways to tell if a low-risk tumor has progressed, and so on.